Cam gear assembly

Abstract

A gear assembly with roller-cam contact by a cam gear with adjacent teeth forming a notch which defines a lobular periphery and a roller gear with a plurality 10A of rotatable rollers 10 is disclosed. Upon rotation, a roller rollingly contacts one of the sides of the lobular periphery and rollingly travels along the lobular periphery to rollingly contact the remaining side of the lobular periphery and with at least one of the teeth of the cam gear being in rolling contact with both a roller in an approach phase and with a roller in a recess phase to provide mechanical communication between the roller gear and the cam gear. A method of manufacturing the cam gear and the roller gear is also disclosed.

What is claimed is: 
     
       1. A gear assembly with a constant angular-velocity ratio comprising: a roller gear with a plurality of rotatable rollers with each roller having an axis and a radius and being equally spaced apart relative to one another in rotational symmetry; and   a cam gear having a plurality of teeth with adjacent teeth forming a notch defining a lobular periphery having a pair of sides, said plurality of teeth equally spaced apart relative to one another in rotational symmetry to provide a cam-gear profile such that, in use, upon rotation of said cam gear and said roller gear, each said rollers rollingly contacts one of said sides of said lobular periphery and rolls along said lobular periphery, wherein at least one of said teeth of said cam gear is in rolling contact with both a roller of said roller gear in an approach phase and with a roller of said roller gear in a recess phase to provide mechanical communication between said roller gear and said cam gear at a constant angular-velocity ratio without loss of contact between said cam-gear tooth and said rollers and where a pitch curve of said cam-gear tooth along which said axis of each said roller travels is defined by said cam-gear profile distanced by said radius of each said roller from each said cam-gear tooth, and x and y coordinates of said pitch curve in the origin of the center of said cam gear are defined by: ##EQU6##  where: r=angular velocity ratio of cam gear and roller gear θ o  =2π radian divided by the number of rollers of roller gear   d=center distance between cam gear and roller gear   θ.sub. = angle from the center distance line   R 1  =radius of roller gear   θ 1  =angle varying between -β and 2θ o  +β in which angle β satisfies the following condition: ##EQU7##     
     
     
       2. The gear assembly of claim 1, wherein said roller gear and said cam gear are mounted on a parallel shaft, respectively, and each said roller of said roller gear has a cylindrical shape and each said notch of said adjacent teeth of said cam gear has a surface contour to matingly receive said cylindrical shape. 
     
     
       3. A gear assembly with a constant velocity ratio comprising: a roller gear with a plurality of rotatable rollers with each roller having an axis and a radius and being equally spaced apart relative to one another in rotational symmetry; and   a cam gear in a plane with a plurality of teeth, each tooth having an axis extending perpendicular to said plane of said cam gear to define a cam gear rack, adjacent teeth forming a notch defining a lobular periphery having a pair of sides, said plurality of teeth being equally spaced apart relative to one another in translational symmetry to provide a cam-gear profile such that, in use, upon rotation of said roller gear each said roller rollingly contacts one of said sides of said lobular periphery and rolls along said lobular periphery with at least one of said teeth of said cam gear rack in rolling contact with both a roller of said roller gear in an approach phase and with a roller of said roller gear in a recess phase to provide mechanical communication between said roller gear and said cam gear rack at a constant ratio of translational velocity of said cam gear rack to the angular velocity of said roller gear, a pitch curve of said cam-gear tooth along which said axis of each said roller travels is defined by said cam gear profile distanced by said radius of each said roller from each said cam-gear tooth, and x and y coordinates of said pitch curve in the origin at the center of said roller gear are defined by:   x=-R.sub.1 θ.sub.1 -R.sub.1 sin(θ.sub.0 -θ.sub.1)       y=R.sub.1 cos(θ.sub.0 -θ.sub.1)        where: R 1  =radial distance from rotational center of roller gear to each center of rollers   θ 0  =2π radian divided by the number of rollers of roller gear   θ 1  =angle varying between -φ and 2θ 0  +φ in which the angle φ satisfies the following condition:   sin(φ+θ.sub.0)=φ+θ.sub.0 /2.